Modulation of the Electrical Properties of VO2 Nanobeams Using an Ionic Liquid as a Gating Medium

Vanadium dioxide (VO2) is a strongly correlated transition metal oxide with a dramatic metal-insulator transition at 67 degrees C. Researchers have long been interested in manipulating this transition via the field effect. Here we report attempts to modulate this transition in single-crystal VO2 nanowires via electrochemical gating using ionic liquids. Stray water contamination in the ionic liquid leads to large, slow, hysteretic conductance responses to changes in the gate potential, allowing tuning of the activation energy of the conductance in the insulating state. We suggest that these changes are the result of electrochemical doping via hydrogen. In the absence of this chemical effect, gate response is minimal, suggesting that significant field-effect modulation of the metal-insulator transition is not possible, at least along the crystallographic directions relevant in these nanowires.